Hydrolysis of cellulose esters



andja basic nitrogen compound. v

Patented May 7, 1935 a a I 2,000,620;

HYDROLYSIS 2,000,620 v or OELLULOQSE Es'rms Cyril J. Staudand Louis Minsk, Rochester, N. ,Y.,,assignors to Eastman Kodak Company, Rochester, N. Y.; a corporation of New York No Drawing.

Application February 17, 193 2,- Serial no. 5 93,6 84 l 20 Claims. (cl gep z y;

The present invention relates to the hydrolysis of fully esterified esters of cellulose and especially those produced by the fibrous esteriflcation' of cellulose, by meansof the mixture of a'phenol The hydrolysis or saponificati on of cellulose esters such as cellulose acetate to convertsuc'h esters to acompound of favorable solubility has been known in the art for a long time. For instance cellulose triacetate has been allowed-to stand in aqueous acid mixtures until the acetyl content has been reduced to the desired extent and a state of acetone-solubility attained, some experimenters have pointed out that the acids which are capable of effecting saponification of cellulose acetate have 'asevere action on the celluloseitself which may cause aweakenlng of the entire cellulose structure'of the ester. We have found that any danger due to thedegradation of the cellulose structure by acid hydrolysis baths is completely eliminated by the hydrolysis of the cellulose ester in our hydrolysis bath which is of an alkaline nature. V v

' Heretofore allprevious attempts tohydrolyze cellulose esters by means of alkaline baths have been failures, as the product produced by those processes has been'insoluble (or poorly soluble) 'in' acetone and the conversion of the cellulose ester-usually took place with irregularity; For example some of the products formed in these prior alkaline hydrolysis'processes exhibit a much greater amount of hydrolysis than other portions in the same mixture. Also in those alkaline hydrolysis processes in which caustic materials such as sodium hydroxide havebeen. employed 'a weakening 'of the structure of'the cellulose apparently'takes place which is fully as great as in the case of the. acid. hydrolysis of cellulose esters in the presence of strong mineralacids.

We'hav found'a-method of hydrolyzing .celi lulose esters in an alkaline solution in which there is no apparent weakening of the cellulose structure of those esters. We have found an al- .kaline' method of hydrolyzing cellulose acetate in which an acetone-soluble produce of good appearance; and 'high acetone-viscosity is obtained,

indicating that no breakdown of thecellulose molecule has occurred.

wwehave found that cellulose esters-may be hydrolyzed by treating them with a phenol mixed sis may be accomplished at a higher temperature and within a shorter time than is usually permissible in the hydrolysis of cellulose esters V in which ,there is danger of degradation. at higher lulose ester was separated'therefrom by precipitation in hotalcohol. The resulting ester sepknown at the present time. with a basic nitrogen compound. The hydrolytemperatures from the reagents ordinarily employed in those processes. Obviously lower tem-l peratures together with, alonger time of treatment, are permissible in our hydrolysis process but such lengthening ofthe process isundesir 6 able from an economic standpoint. a As mentioned before our process is applicable to cellulose esters in generalsuch as precipitated from the reaction mixture in which they were produced and is especially applicable to the hydrolysis of cellulose ;este'rs. produced in fibrous esterification processes such as one in which carbon tetrachlorideor benzeneis employed as the non-solvent. Spray dried cellulose esters from which the acid; has been eliminated may also be hydrolyzed by the processvofour invention. .1 .fIhe followingi specificexamples are "illustrative pf our invention and are in nowise limiting aster the scope 'thereof; V w r f. .f .j -ij'fEa ampl e f j 25 lbs. of a cellulosetriacetate resulting from the'fibrous acetylation ofv cellulose was dissolved lbs. of .phenol '(Eas'tman' white label). 25 About 23 lbs. of'a. 28%";aqueous ethylar'ninesolution was then added and the mixture was placed in an oven at a temperature of 53 .6. Samples were removed at intervals and the'celarated from theldope was washed ireeof phenol with alcohol, .followed' by washing with water,

and drying? The ester from each interval-was Aoetyl content Time of treatment S olubility To 50'lbs. of phenol was added 10 lbs. of 28% aqueous ethylamine solution and 10 lbs. of cellulose triacetate. The mixture was maintained at about 50-55 C. for 6 hours, at the end of which time the hydrolyzed acetate was precipitated by pouring into hot alcohol. The precipitate was thoroughly washed with hot alcohol, then with hot water and then dried. The product was found to be soluble in acetone in which it gives a brilliant smooth dope of very good viscosity. 4

Example III The process in Example II was repeated except that 10 lbs. 28% aqueous ammonium hydroxide was employed instead of ethyl amine.

tained.

The products obtained by the hydrolysis of cellulose esters are eminently suitable-for ;the

production of skins or sheeting which may be employed for making photographic film, wrapcellulose ester is suitable. The products formed 7 by our process may be mixed with plasticizers such as triphenyl phosphate which are, wellknown as plasticizers for celluloseacetate. Various other plastic materials such as gums, waxes, resins, other cellulose'esters etc. which are compatible with the hydrolized esters 'producedby our invention may also be incorporated with those hydrolyzed-esters if desired. x

Although our invention is concerned primarily with the hydrolysis of cellulose triacetate to ace: tone-solubility, due to the commercial importance of acetone-soluble cellulose acetate at the present time, it is also applicable to the higher esters of cellulose both simple and mixed whether or not they are originally acetone-soluble. For example cellulose butyrate or cellulose acetatebutyrate even though they be soluble in acetone may be hydrolyzed by our process to give products having properties differing from the completely esterified esters of cellulose. 'As disclosed in Malm and Fletcher application Serial Number 551,546 filed July 17, 1931, various mixed organic esters of cellulose when hydrolyzedgive films'of greater flexibility from some organic solvents than the corresponding unhydrolyzed esters so that even though the fully esterfled esters may be originallyacetone-soluble, the hydrolysis of such esters may bedesirable. v

Although the basic nitrogen compounds given in the examples were employed because of their commonness and availability, any other basic nitrogen compound which is compatible with the process of our invention maybe employed. Instead of ethylamine, amines which possess some other alkyl group may be employed. The use of methyl amine is restricted to some extent due to its limited solubility in water but where this factor is immaterial it may be employed in our process as the'basic nitrogen compound. Amines which contain one or more phenyl groups are also restricted as to use due to their slight solubility in water. Besides the organic derivatives of ammonia known as primary amines, the secondary Y and tertiary amines which have more than one alkyl (or like) group attached to the nitrogen atom may be employed in our process. Any chemical compound may be employed in our process which belongs to the class known to chemists as the basic nitrogen compounds and A product equal to that produced in Example IIwas obwhich is physically compatible with the materials employed in the process.

Other phenols than phenol itself such as a cresol may be employed in our hydrolysis process,

however due to the commonness of phenol itself, and its satisfactory behavior in our hydrolysis process, its use is preferred at the present time. Various other modifications and variations such as in time, temperature, proportions etc. which are a matter of individual judgment and technique also come within the scope of our invention.

We claim as our invention: 1. The hydrolysis of an organic ester of cellu- 'lose'in 'a hydrolyzing bath essentially consisting of a phenol and a basic nitrogen compound.

2. The hydrolysis of an organic ester of cellulose in a hydrolyzing bath essentially consisting of a phenol and a compound have the formula:

in which X, Y or Z, each may be either a hydrogen, alkyl or aryl group. I

3. The hydrolysis of an organic ester oi! ceHulose in a hydrolyzing bath essentially consisting of phenol .and a basic nitrogen compound.

4. The hydrolysis of an organic ester of cellulose in'a hydrolyzing bath essentially consisting of phenol and a compound having the formula:

i e -z in which X, Y or Z each may be either a hydrogen, alkyl or aryl group.

5. The hydrolysis of an organic ester of cellulose in a hydrolyzing bath essentially consisting of a phenol and a basic nitrogen compound containing an NH group.

6. The hydrolysis of an organic ester of cellulose in a hydrolyzing bath essentially consisting of a phenol and a basic nitrogen compound containing an NHz group. I

,7. Thehydrolysis of a fatty acid ester of cellulose in a hydrolyzing bath essentially consisting of a phenol and a basic nitrogen compound.

8. The hydrolysis of a fatty acid ester of cellulose in a hydrolyzing bath essentially consisting of ya phenol and a compound having the formula:

in which X, Y, or Z each may be either a hydrogen, alkyl or aryl group.

9. The hydrolysis of a fatty acid ester of cellulose in a hydrolyzing bath essentially consisting of phenol ancla basic nitrogen compound.

10. 'Ihe'hydrolysis of a fatty acid ester of cellulose in a hydrolyzing bath essentially consisting of phenol and a compound having the formula:

-Y x-N in which X, Y or Z each may be either a hydrogen, alkyl or aryl group.

11. The hydrolysis or an organic ester of cellulose-in a hydrolyzing bath essentially consisting of a phenol and an alkylamine.

12. The hydrolysis of an organic ester of celluloses in a hydrolyzing bath essentially consisting of phenol and an alkylamine.

13. The hydrolysis of cellulose acetate in a hydrolyzing bath essentially consisting of a phenol and a basic nitrogen compound.

14. The hydrolysis of celluloses acetate in a hydrolyzing bath essentially consisting of a phenol and a compound having the formula:

Y X-N z in which X, Y or Z each may be either a hydrogen, alkyl or aryl group.

15. The hydrolysis of cellulose acetate in a hydrolyzing bath essentially consisting of phenol and a basic nitrogen compound.

16. The hydrolysis of cellulose acetate in a hydrolyzing bath essentially consisting of a phenol and an alkyl amine.

1'7. The hydrolysis of cellulose acetate in a hyhydrolyzing bath essentially consisting of phenol 10 I and ammonium hydroxide.

CYRIL J. STAUD. LOUIS M. MINSK. 

